Air-cooled condenser for refrigerating machines



June 22 1926. 1,589,412

J. E. MITCHELL AIR COOLED CONDENSER FOR REFRIGERATING MACHINES Filed March 17 1924 Patented June 22, 1926.

PATENT OFFICE,

JOHN E, MITCHELL, OF ST. LOUIS, MISSOURI.v

AIR-CO OLED CONDENSER FOB REFRIGERATING MACHINES.

, Application filed mm 17, 1924. .Serlalll'o. 699,701.

This invention relates to a novel aircooled condenser -for use, especlally, wlth small s1ze mechanlcal' refrigerating machines of the type adapted for household refrigeration, ice-cream cabinets, and the like, and which type of machines it isdesirable to have as compact and simple in construction as possible.

The use of a water-cooled condenser in which water is circulated about the condensing coils to liquefy the compressed refrigerant presents various objections, among wh1ch may be mentioned the extra piping required, the necessity of employing automatic means for turning on and oil the water, the expense of using the water itself, and the cost of making connections to the water supply.

The desirability, therefore, of using an air-cooled condenser is recognized, but the objections to the use of air-cooled condensers as heretofore constructed has been, chiefly, that they do not provide suflicient surface within the space permitted for household or other small refrigerating units to adequately condense the compressed refrigerant.

This objection I aim to overcome by the resent invention, in which the condenser is so designed that air may be caused to circulate freely around the condenser coils, and the structure, while compact in form, afit'ords adequate surface to completely liquefy the compressed refrigerant passing through the condensing conduits of the same.

With the above aim in view, the invention comprises a plurality ofcoiled tubes arran ed in paralleT within and around a foraminous shell to which said tubes are rigidly connected, the corresponding 0 posite ends of the tubes being connecte to headers from which lead, respectively, inlet and outlet pipes, with means for inducing a forced draught of air around, and through the space between, the coils of said tubes.

4 The invention isillustrated in the accompanying drawing, in which a Figure 1 isa vertical sectional view of ,a condenser constructed according to my .-1nvent1on;

Figure 2 1s a sectional plan v ew thereof; and

Figure 3 1s a v1ew partly in elevation and partly in sect on illustrating a modified arrangement for inducing a draught'of air for cooling the coils of the condenser.

Referring now to Figure 1 of the drawmg, the numeral 1 indicates a cylindrical shell, preferably made of stout wire screen, co led within and around which, in, parallel relation, are two tubes, 2 and 3, respectlvely, the tubes at the upper end of the screen entering and being secured to a header 4, with which is connected an inlet pipe 5, leading from the compressor of a re rigerating system. At the lower end of the condenser, the ends of the tubes are 'secured to -and communicate with a header thereof. The shell 1 is mounted at its bot-- tom on a flanged ring 8, by means of which it is secured to a suitable base 9.

The construction described provides, as will be seen, a central space surrounded by the condensing coils, and this space;

lends itself readily to securing the intimate contact of air with the condenser tubes by inducing therethrough or therein a forced draught of air. This result is facilitated by c osing one end of this space, as hereinafter explained, to insure the passage of the1 air from the space outward through the 001 s.

The means which I em loy for forcing air around, and through t e space between the coiled tubes, comprises a motor-driven fan, suitably located with reference to the condenser, the motor being also used for operating the compressor.

In the use of my condenser in a complete, self-contained machine .for: household 'refrigera'tion, ice-cream cabinets, or similar purposes where a corn act and h1gh%yefi1- cient design is essentia I find 1t pre e'rab'le to locate the motor 10 in the central space formed by "the; condenser and on the same base 9 on which the condenser is carried. Mounted on the upper end of the armature shaft 11 of the motor, is a suitable fan 12,

e by means of which a strong current of air is drawn throu h that portion of the spiral coils extending elow the fan, and the same and insert the same through the central opening in the top of the condenser, supporting it thereon by means of a flange 14 provided at the .top of the cone. This flanged cone operates to close the top of the central space of the condenser and thus prevent the direct passage of the air out of the top of said central space, and while other forms of closure could be used, I prefer a cone by reason of the fact that it will operate to cause the more uniform passage of the air outward between the coils of the condenser around the entire circumference of the central space. The lower endof the -motors vertical armature shaft 11 extends I use for driving the compressor of the system.

In operation, compressed gas is piped into the upper end of the condenser through the inlet pipe 5 and the header 4, the interior of the latter communicating with the upper ends of the internal coil 2, and the external coil 3. Each cone having only one-half of the gas to condense, has ample area to carry the condensed liquid to the bottom on a very slight incline so that no diflic'ulty with trapping is encountered. When the liquid flows out at the lower ends of the two coils into the lower header 6, it is conducted thence through pipe 7 to the distributor, expansion valve, or the like, through which it passes to the place of use.

Obviously, various ways, other than that shown in Figure 1, of inducing a forced circulation of air around, and through the spaces between the coils of the condenser could be employed. For example, in Fig ure 3, I have shown a shaft 16 extending upward through the central space of the condenser and journalled in bearings provided in a skeleton frame 17 at the to of the condenser and in the base 9 at the ottom, and on the upper end of this shaft'and on the top of the condenser, I mount a suction fan 18, preferably of the sirocco type, through an opening 19 in the lower casing wall of which air may be drawn in from I the condenser and expelled laterally by the meagre side of the condenser through the spaces between the coils and through the opening in the shell 1, and expelled atthe top of the condenser. In Figure 2, the air is drawn from theoutside through the coils and shell at the lower art of the condenser and forced outwar ly through these parts at the upper end of the condenser.

Without further illustration, it will be plain that a fan could be located in an opening in the base 9 and force air upward in the central space formed by the foraminous cylinder and condensing cdils, and by having the upper end of this space closed the air would be forcedout through the spaces between the coils,

The signal advantages of a condenser of this type are its compact form, its'relative" rigidity of the coils, and, finally, the ample area afforded to carry the condensed liquid to the bottom of the condenser on .a very slight incline, due to the employment of two coils.

I have shown and described the coils 2 and 3-as being in parallel relation. This enables me to cause the convolutions of the inner coil to break joint with the convolutions. of the outer coil, or, in other words, to present a staggered relation, which materially aids in insuring contact of air with the surface of the tubes, and in deflecting the air around the tubes. The invention, however, would not be limited to this arrangement, and, if desired, the coils could be wound in opposite directions within and around the shell supporting them.

I claim:

1. A condenser for use in refrigerating systems, comprising an open-work cylinder, a pair of tubes coiled, respectively, withln and around said cylinder and having their coils secured to the wall of said cylinder and their opposite ends located, respectively, at the top and bottom of the cylinder, an upper header secured to and communicat ng with the upper ends of said coils and having an inlet, a lower header secured to and communicating with the lower ends of said coils and having an outlet, and means for inducing a forced draught of air throu h the space surrounded by said cylinder and coils, and around and through the spaces between said coils.

2. A condenser for use in refrigerating systems, comprising an open-work cyhnder, a pair of tubes coiled, respectively, wlthrn and around said cylinder and havin the r coils secured to the walls thereof an then opposite ends located, respectively, at the top and bottom of the cy mder, an upper header secured to and communicatmgwith theupper ends of said coils and having an inlet, a lower header secured to and communicating with the lower ends of said coils and having an outlet, means for forcing a blast of air upward in the space surrounded by said cylinder and tubes, and a closure for the upper end of said space.

3. -A condenser for use in refrigerating systems, comprising a foraminous cylindrical shell, a pair of tubes coiled around and within the wall of said shell and having their opposite ends located, respectively, at the top and bottom thereof, an upper header connected to and communicating with the upper ends of said tubes and having an inlet, a lower header connected to and com- -municating with the lower ends of said tubes and having an outlet, a base sup orting said condenser, a motor mounte on said base and extending upward into the space surrounded by said tubes and shell,

. a fan located on the upper end of the armature shaft of said motor, and a closure for the upper end of said space.

4:. A condenser for use in refrigerating systems, comprising an open-work cylinder, a pair of tubes coiled within and around said cylinder in parallel relation, said coils being secured to the wall of said cylinder and having their upper and lower ends lo- ,cated, respectively, at the top and bottom or the cylinder, a header connected to and communicating with the upper ends of said tubes and having an inlet, a header connected to and communicating with the lower ends of said tubes and having an outlet, and means for forcing a draught of air from the central space formed by'the coils and cylinder outward through the spaces between said coils.

In testimony whereof, I have hereunto set my hand.

JOHN E. MITCHELL. 

